Coating head dike



May 1, 1962 F. w. MCCAULIFF 3,032,007

COATING HEAD DIKE Filed May 1, 1959 INVENTOR. Francis W. McCouliff BYM/Eavflj WJ, M

ATTORN EYS 3,tl32,0tl7 COATTNG HEAD BIKE Francis W. McQauliif, 225 Ssouth Sh, Fitchburg, Mass. Filed May 1, 1959, Ser. No. 810,332 2 Claims. (Cl. 118-407) This invention relates to apparatus for coating paper and the like flexible sheet materials and more particularly to an improvement in a coating head element or dike. The invention dike aflords a fluid pressure seal between the coating head and the sheet to be coated which prevents both leakage of the coating fluid and scoring of the coated sheet, and secures also a desired narrow and uniform uncoated sheet edge or deckle.

The invention will be better understood from a consideration of the following specification taken in conjunction with the accompanying drawings in which FIG. 1 is a perspective view of a coating head incorporating the invention dike, shown as applied to a coating roll;

FIG. 2 is an outer side elevation of the dike;

FIG. 3 is a perspective view of the dike as seen from the inner side; and

PEG. 4 is a front elevation of the dike as partially "broken away to show the fluid passages therethrough.

In the coating of paper and the like flexible sheet materials a long sheet if? is rapidly passed over a series of rolls including a rubber coating roll 11, FIG. 1, against which is held a coating head providing a fluid reservoir or trough, the sheet 19 in passing over the roll defining a downward moving front wall of said trough.

The coating head comprises a doctor or scraper blade 12 which is supported at its back edge, as between the holding or clamp jaws 13. The jaws 13 will be understood to be adjustably mounted for supporting and biasing the blade 12 against the roll at the desired angle and pressure.

The back wall of the coating head is shown as a plate 14 mounting means such as the dovetails 14a for lateral adjusting support of the side or end elements of the coating head, comprising dike holder plates 15 to which are secured, as by bolt fastenings 15a, the dike plates 16.

The dikes 16 are shown more particularly in FIGS. 2-4 to comprise arcuate plate members having front faces 17 opposing and curving conformantly to the roll with which the coating head is designed for use, and bottom faces 18 opposing the blade 12 and stepped as at 18a for fitting over the upper jaw 13. The dike plates 16 are further defined as left and right hand members having oppositely facing outside and inside walls 19, Zil.

Herein also the dikes 16 are widened at the front by inwardly projecting flanges 17a, FIG. 3. The plate width between the side walls 19, 2% may be, say, in. and the flange 17a may project laterally, say, in. and extend, say, /2 in. rearwardly from the front face. The flanges 17a are also undercut rearwardly to present a bottom face 18b which angles upward from the main bottom face 18.

The dikes are herein as conventionally cast or otherwise formed from bronze or the like rigid durable material impervious to the coating fluid.

In the operation of the described coating apparatus the coating fluid, which is supplied at the open topof the trough, is absorbed by the sheet 10 in a thickness limited in part by the pressure of the blade 12;, and over a width determined roughly by the lateral spacing of the dikes 16.

The width desired for the coating is one which leaves a relatively narrow and uniform uncoated paper edge or deckle.

The dikes 16 are conventionally one inch (1 in.) or more in width, but the deckle may ideally be appreciably less than that. For particular example, where it is de- United States Patent possible Widening to the full width of the dike.

7 Patented May-1, 1962 "ice sired to produce two 32 in. coated rolls from a 65 in. un-

coated roll it is necessary to hold the deckle to within a yields a turbulence at the top of and an induced or increased pressure at the bottom of the, say, 5-7 in. deep, more or less viscous coating fluid volume. Thus, while the spacing may widen toward the top as shown, FIG. 2, the dikes 16 are required to be positioned extremely close to, say, 0.006'in. from, the roll 11 at their front-bottom faces intersections or points.

For the fluid pressure induced as described at the bottom of the coating head trough is such that the mentioned film may be carried all the way across the dike face, and the deckle may thus be lost altogether, if the dike-roll spacing is increased only slightly, or to more than, say, 0.609 in. On the other hand, thedeckle may be excessively widened to the full dike width if the dike-roll spacing becomes too small, or-is reduced to less than, say, 0.003 in.

The indicated close ordering and accurate control of the coating head and dike position is required further and more generally to prevent leakage of the fluid past, and scoring of the roll by, the dikes. More particularly, if the dikes are allowed in operation to move away from the roll there will result in excessive side leakage of the coating fluid across the front faces of and particularly towards the bottoms of the dikes. On the other hand, if the dikes are permitted too great a shift towards theroll they will marker raise a welt on the edge of the paper,

and, on further closing, will frictionally engage, heat, expand and hence score the roll.

The too close spacing of the coating head from the roll may-result also in the downward deflection of the wiping lade 12 away from its engagement with the underside of the dike, producing bottom leakage of the coating fluid through the gap thus opened up between'the blade and the dike bottom face 18.

.But, due to the vibrating and influencing otherwise of the heavy coating head parts in the high speed operation of the apparatus, the spacing of the dikes from the roll cannot as a practical matter be controlled or held within the required range, having the indicated narrow limits. More particularly, the usual coating heads exhibit uncontrolled shifting towards and away from the roll in excess of those limits, so that the operation of conventional paper coating apparatus must frequently be stopped to permit the necessary backing off or setting up of the head assembly. The indicated adjustment of the coating head to correct for leaks at, or heating of the roll by, the dikes must in fact be madeseveral times a day, the apparatus being almost never left alone for more than an hour.

The described coating head shift will be understood commonly to require also that the paper or like sheet be excessively trimmed. That is, the sheet must be trimmed at both edges by an amount allowing for the indicated variation in the deckle, and more particularly for its Such trimming may reduce the roll to a width less than that which permits its economic division into the maximum number of standard width coated rolls. So that the excess or waste involved, in the trimming of the sheet to spsaoov the width left -between the deckles, is not merely of the wider 'deckle but may amount to nearly one-half the width of the roll.

With each interruption'for repositioning of the coating head it is necessary-to shut down the machine, drop the coating head, dump the coating, dry the machine, and then string up the paper again on the machine.

It will be readily apparent that this involved procedure compels excessive lost time on the machine, and significantly adds also to the labor cost of the'operation. Thus the solution of the dike position controlling and adjusting problem here concerned has beena long and acutely felt want, in the construction and operation of coating machines.

This invention prevents the occurrence of both leakage and friction at the dikes and provides also the desired narrow and uniform deckle by introducing at the dikes an opposing-or back fluid pressure, which pressure acts and may be regulated to contain or counterbalance the coa-tingfluid pressure, particularly the pressure induced as described in the bottom region of the coating head trough and tending there to produce the mentioned side leaks across the lower dike front faces.

In containing the coating fluid as against the side and also bottom leaks the fluid pressure means of the invention give the dikes, in effect, a zero clearance from the coating roll. The invention secures also the effective closing and-sealing of a wider than usual dike-roll spacing, whereby frictional engagement of the dikes with the roll is prevented, under normalcoating head shift.

In accordance with the invention and for introducing or admitting the opposing or counterbalancing pressure fluid one or more inlet passages 21 are formed or cut laterally or from side to side through the dikes is, as

best shown in FIG. '4. "Ihe fluid inlets '21 may be of a number and form as appropriate to the pressure and volume desired for the containing fluid, and are herein shown for convenient example as two straight bores exiting inwardly at relatively small or jet forming openings of, say, 71 in. diameter.

To produce acounterbalancing pressure in the described region of induced or maximum coating fluid pressure the passages 21 are arrangedclose to, say, A in. back from, the dike front faces 17, with a vertical spacing of, say, /2 in. on centers, and with a downward and also forward inclination calculated to provide the maximum counterbalancing pressure at the .points of the coating fluid volume, or in other words at the junction of the blade and roll. A pressure passage inclination found suitable is herein shown as directing the jet streams from the inlet openings downwardly as if to impinge on the blade 12 somewhat inwardly of the dike front flanges 17a.

The dikes 15 are further modified in accordance with the invention to provide recesses or chambers 22 in which the pressure of the coating fluid is reduced, and by means of which coating fluid is reduced, and by means of which also the dike face is narrowed and the desired narrow uniform decide is achieved. As herein embodied the chambers 22 are formed by recessing the dike front faces 17 at and from the bottom'of the flanges 17a, to present a chamber back face 17!) generally paralleling main front face 17 and inclining forwardly to merge therewith to, say, 3 in. from the dike bottom. The recessing at 17b is of the full flange or in. width leaving to the plate front wall there a width of in. and defining a chamber side wall 20a of, say, /s in. depth and in which the inlets 21 are laterally centered. The recessing 17!) results further, and by reason of the mentioned rearward undercutting llfib in the spacing of the bottom edgeof the flange 17a from the blade 12 as shown, FIG. 4.

Fluid conduit means are provided for supplying pressure fluid to the inlet Ports 21, the same herein embodied as brass or the like tubes 23 welded or otherwise fixed to the dike outside walls 19, and which are seen also from FIG. 1 to project upwardly of the coating head and there it turn away from the roll 11, and to be fitted at their rea minimum or bottom roll-dike spacing or clearance of,

say, 0.010 in. The coating fluid is supplied to the open top reservoir in the usual manner and will when the ma chine is started beagitated andpressured as already described. To contain the coating fluid and particularly at the indicated pressure points, pressure fluid is conducted from a supply, as through tubes 24, to the dike tubes 23, then through the passages 21 by which it is directed downwardly-inwardly to the chambers 22. The pressure fluid, which maybe air or other gas, or it may bethe coating fluid itself, is supplied at a soft pressure of, say, 5-l0 lbs. such as allows the desired creep of the coating across the back walls 17 b to the side walls 20a of the recesses 22, while still affording effective zero clearance at and so preventing leakage at the dike front faces 17.

It will be understood that with the appropriate counterbalance pressure .the openings between the dikes and the roll is elfectivelyclosed and sealed, within the expected limits of coating head shift, notwithstanding the initial dike-roll clearance is widened as above indicated to assure against closing of the dikes, subject to said normal coating head shift, to frictional engagement with the roll. In this the pressure fluid forced into the coating head through inlets '21 is considered to diffuse in the chambers 22 and to form there a fluid volume pressing inwardly against and neutralizing or at least substantially reducing the pressure of the coating fluid there.

The outward pressure is limited inthe chambers 22 also by the above described spacing of the flange bottom lflb from the plate 12 whereby some of the coating fluid drawn to the bottom of the chambers 22 passes out rearwardly away from the dike face.

.Thus the pressure fluid may be accurately controlled to and aflords a seal infinitely deformable to maintain the same straight coating edge line at the chamber 22 throughout the paper coating operation.

With the apparatus of this invention, then, both the friction heating and scoring of the roll and also the leaking of the coating fluid are avoided, as is the necessity for fine adjustment of the dike. Any needed leakage preventing adjustment of the apparatus is'had rather and merely by adjusting the pressure of the counterbalancing fluid, and without interruption of the coating process.

It will be understood that my invention is not limited to the particular embodiments thereof illustrated and described herein, and I set forth its scope in my following claims.

I claim:

1. In an apparatus providing a reservoir for supplying coating fluid to a roll carried sheet and having a bottom element and at its ends upstanding dike plates formed with front faces adapted to oppose said sheet and bottom faces intersecting said front faces and adapted to oppose said bottom element, the improvement in dike construction which consists of the plates having pressure chambers at said intersecting front and bottom faces and formed by recessing the inner sides of said front face upwardly from said bottom faces, the dike plates having also fluid passages opening into said chambers and means for connecting said passages to a fluid source, whereby to supply to said chambers fluid which at counterbalancing presure is effective to confine said coating fluid against leakage around said dikes and thereby to secure a uniform deckle to said sheet.

2. In an apparatus providing a reservoir for supplying coating fluid to a roll carried sheet and having a bottom element and at its ends upstanding dike plates formed with front faces adapted to oppose said sheet and bottom faces intersecting said front faces and adapted to oppose References Cited in the file of this patent said bottom element, the improvement in dike construc- UNITED STATES PATENTS tion which consists of the plates having passages exiting inwardly adjacent the points of intersection of their front 2031'387 ichwarz 2 and bottom faces, and fluid conduit means associated 5 2,168,991 ankes et 19 9 with said plates, said means communicating with said 6 gg et i eanddtdf l fl'd lh'- r passag s a HP 6 or coup mg to a m supp y w ere 2,918,899 Munten et a1. Dec. 29, 1959 by to supply at said intersections fluid which at counterbalancing pressure is eifective to confine said coating fluid against leakage around said dikes and thereby to secure a 10 uniform deckle to said sheet. 

